OS X 10 11 SIP对NVRAM的重大影响

• SIP是OS X El Capitan中新增的一大特性。
• NVRAM断电后不丢失其中保存到信息。

这两大因素给予了我长达半个月的软硬件故障的困扰，几乎走投无路。

具体症状是每次启动黑苹果都会出现的错误报告，偶尔还附带着屏幕上的条带状花屏：

Anonymous UUID: 0E139575-7B5D-DA10-F254-4B64727D19C2

Mon Oct 19 14:41:14 2015
panic(cpu 3 caller 0xffffff7f81c7abcc): pmLock: waited too long, held by 2@0xffffff80002e5062
Backtrace (CPU 3), Frame : Return Address
0xffffff810af93cc0 : 0xffffff8000223139
0xffffff810af93d40 : 0xffffff7f81c719bb
0xffffff810af93d80 : 0xffffff7f81c6b261
0xffffff810af93e70 : 0xffffff7f81c69d06
0xffffff810af93f30 : 0xffffff80002de4dc
0xffffff810af93f50 : 0xffffff80002378fa
0xffffff810af93f90 : 0xffffff8000237c48
0xffffff810af93fb0 : 0xffffff80002d7c67
Kernel Extensions in backtrace:
com.apple.driver.AppleIntelCPUPowerManagement(217.92.1)[1A9E8072-CBF3-39C2-8514-B8176259D3D7]@0xffffff7f81c68000->0xffffff7f81c92fff

BSD process name corresponding to current thread: kernel_task
Boot args: j2b;1oModel: MacBookPro8,1, BootROM MBP81.0047.B27, 2 processors, Intel Core i5, 2.49 GHz, 8 GB, SMC 1.68f99
Graphics: Intel HD Graphics 3000, Intel HD Graphics 3000, Built-In, 512 MB
Graphics: Display, PCIe
Memory Module: BANK0/DIMM0, 4 GB, DDR3, 1333 MHz, Kingston, M471B5273DH0-CH9
Memory Module: BANK1/DIMM0, 4 GB, DDR3, 1333 MHz, Hynix/Hyundai, HMT351S6CFR8C-PB
PCI Card: sppci_expresscard_name
PCI Card: sppci_expresscard_name
PCI Card: sppci_expresscard_name
Serial ATA Device: TOSHIBA MQ01ABD050, 500.11 GB
Serial ATA Device: hp DVDRAM GT50N
USB Device: Hub
USB Device: Wacom Wireless Receiver
USB Device: HP HD Webcam [Fixed]
USB Device: Bluetooth USB Host Controller
USB Device: USB Receiver
USB Device: Hub
USB Device: USB Keyboard
USB Device: Vendor-Specific Device
USB Device: USB Flash Disk
Thunderbolt Bus:

通过无尽的盲目探索，终于意识到应当关闭SIP，重置SIP。

以下各步操作（命令）虽并不都必需，但可充分排除故障：

csrutil clear

csrutil disable

• csrutil系列命令仅限于OS X El Capitan Recovery 分区中使用

sudo nvram -c